MIT boffins have emerged from their smoke filled labs with an advanced manufacturing approach for lithium-ion batteries which promises to slash the cost while also improving their performance and making them easier to recycle.
The method will be marketed by a spinoff company called 24M which claims to have re-invented the process of making lithium-ion batteries.
Yet-Ming Chiang, the Kyocera Professor of Ceramics at MIT, and a co-founder of 24M said that the existing process has hardly changed in the two decades since the technology was invented, and is inefficient, with more steps and components than are really needed.
The new process is based on a concept developed five years ago by Chiang and colleagues including W. Craig Carter, the POSCO Professor of Materials Science and Engineering. In this so-called “flow battery,” the electrodes are suspensions of tiny particles carried by a liquid and pumped through various compartments of the battery.
The new battery design is a hybrid between flow batteries and conventional solid ones: In this version, while the electrode material does not flow, it is composed of a similar semisolid, colloidal suspension of particles. Chiang and Carter refer to this as a “semisolid battery.”
Chiang said that this approach greatly simplifies manufacturing, and also makes batteries that are flexible and resistant to damage.
We realized that a better way to make use of this flowable electrode technology was to reinvent the manufacturing process.”
Instead of the standard method of applying liquid coatings to a roll of backing material, and then having to wait for that material to dry before it can move to the next manufacturing step, the new process keeps the electrode material in a liquid state and requires no drying stage at all. Using fewer, thicker electrodes, the system reduces the conventional battery architecture’s number of distinct layers, as well as the amount of nonfunctional material in the structure, by 80 percent.
Having the electrode in the form of tiny suspended particles instead of consolidated slabs greatly reduces the path length for charged particles as they move through the material — a property known as “tortuosity.” A less tortuous path makes it possible to use thicker electrodes, which, in turn, simplifies production and lowers cost.
Basically this will cut battery costs by half, and create a battery that is more flexible and resilient. While conventional lithium-ion batteries are composed of brittle electrodes that can crack under stress, the new formulation produces battery cells that can be bent, folded or even penetrated by bullets without failing. This should improve both safety and durability, he says.